As a fluid control device, there is well known a device including a body in which a fluid passage is disposed, a casing which is disposed above the body, a valve body which opens and closes the fluid passage, a valve rod which moves upward or downward so as to move the valve body in an opening or closing direction, a piston which is disposed at the valve rod, and a piston driving unit which drives the piston. In such a fluid control device, its opening and closing states cannot be seen from the outside. Accordingly, in Patent Literature 1, there is proposed a fluid control device to which a function of indicating opening and closing states is conferred.